ANTH 1001 : Anthro Test 1 Day 4
Anthro 9-19-07
Case Studies in Natural Selection
Sickle Cell Trait is a homozygous recessive disorder, the allele is a mutated form of the normal
allele and causes a deffimation of the hemoglobin allele
It causes it to deform and form a sickle like thing, if you have two copies of this you will
have it and frequents a lot of people, severe anemia, pain and usually death with 45 years
of age in America is the life expectancy
They found it highest in the tropical regions of the old world, they began to question why
it is in the areas so high, in western and central Africa it reaches 20percent carry the allele
Why would we still have high frequencies of this when they die off, so they found
that in some areas where it was they found high amounts of Malaria happen, so
they overlap in a way
It is caused by a parasite transmitted by mosquitoes over to humans, they believe
that somehow it uses the red blood cells as the reproduction cycle, and when you
have had it you really can not get rid of it
The hypothesis was that in the areas there is a situation of where Homozygous
normal were more succeptable to Malaria, where Hetero you will have a leg up on
it and possibly not get it
Balanced Polymorphism is the maintenance of two or more alleles in a population
due to the selective advantage of the Heterozygote(Heterozygote Advantage)
Cline is a map that shows the distribution of Alleles
Tay-Sachs in Ashkenazim Jewish population(Mendelian Recessive disorder)
It causes problems in the nervous system, a fatty system builds up in the body because of
an Enzyme doesn’t work properly and the result is the accumulation of fats in the nervous
system, showing around 6 months and dies off after 2-3 years
The alleles are maintained at a high frequency, they found that during WW2 eastern
Jewish populations were heavily discriminated against so in settlements they found that
TB was rampant, except for the Ashkenazim group it was really low so the offspring have
Tay Sachs but not TB
So maybe something in the past that they were carriers to the children, where maybe
Homozygous normal is susceptible to TB where Heterzygous is not but has higher risk of
Tay-Sachs
Document Summary
Sickle cell trait is a homozygous recessive disorder, the allele is a mutated form of the normal allele and causes a deffimation of the hemoglobin allele. They found it highest in the tropical regions of the old world, they began to question why it is in the areas so high, in western and central africa it reaches 20percent carry the allele. Why would we still have high frequencies of this when they die off, so they found that in some areas where it was they found high amounts of malaria happen, so they overlap in a way. The hypothesis was that in the areas there is a situation of where homozygous normal were more succeptable to malaria, where hetero you will have a leg up on it and possibly not get it. Balanced polymorphism is the maintenance of two or more alleles in a population due to the selective advantage of the heterozygote(heterozygote advantage)
